Hey Mike,
Well, the first thing I'm going to say is that that entire sequence (both on the ground and seated) is highly formalised, and requires a bit of adaptation for it to be a "street" effective technique. But I'm sure you can see that already. And that's actually fine, provided it's understood.
For example, the standing version has a shift back and deflection against the first punch (shifting into a "cat stance" to set up for the kick). Against the next punch (a rear, no step from the attacker), it is deflected again with a left palm, while kicking with the left foot to keep the attacker back. There is then a combination to finish. But to look at that first part, the attack is one step and two punches, and as the defenders first movement takes them backwards (out of range of the first punch), and the second, being a rear is actually shorter, the second punch is out of range and won't reach the target. This is why Larry uses no evasion on the second one. A very simple adaptation to make it more realistic (and still a formal, "classical" technique) would be to have the attacker step forward on that second punch, and combine that with the defender simply shifting slightly to the left as they deflect and kick. Then finish as desired.
To make it a "street" technique, change the attack to either a jab/right cross combination (for someone with a little boxing or skill behind them), and lower the kick to the knee, or possibly the hip, and a silght change to the postures to take the formality out of them (that's easier to show than write...).
When Larry shifts to the ground, we again get a very formalised approach. The half-kneel posture the guy on top is using is actually the more common "ground" posture in classical Japanese arts, as it allows you to get up again relatively easily in armour. When doing classical techniques, it's the posture I use. However, for the modern techniques, it is too high, too unstable, and there is too much risk of your leg being grabbed (which is a very bad thing...). But to the formal version...
As with the standing technique, the attacks are again out of range, so it is very safe for Larry to deflect them as they come in. His posture as well, with his right leg raised, but nothing else, is too much of a compromise. Ideally, I would suggest both knees raised, that would make the escape at the end easier to do as well. But I feel that Larry just modelled it on the "cat stance" from the standing version. Understandable, but not ideal. After deflecting both punches, he pulls on the right arm, and raises his right knee to take the guy off. Now, this works because of the top guys very high centre of balance.
To make this a practical street technique, have the guy on top in more of a typical "mount" position, leaning forward and dropping round punches down to the head (very typical, something you see schoolkids doing). The defence here is probably going to be more "jamming" techniques from the inside, rather than deflections from the outside. With the second punch, turn your jam into a catch, and strike to the body with a right punch (the same tactical concept as the kick in the standing version). Then, pull the guy in close, and buck your hips, turning to the side (I would choose your left, as that is the arm you have trapped) to take the guy over and off you. End on top, and finish as desired.
In each case, the art used is still Kenpo. However, it is tempered with an understanding of the realities of different environments. And this can be gained by training in arts that specialise is those different environments, but the base has to be there. Unfortunately for Larry, he doesn't demonstrate the understanding of those evironments here. That's not to say that he doesn't have the understanding, just that it is not shown here. These are formally demonstrated techniques, done for demonstration purposes, and that may go some way to explaining why they are done the way they are. But I personally would still make a few adjustments. The benefit of cross training various systems is that you can "test" your understanding in different environments, too many very established people are highly knowledgable in their own area, and can make anything work for themselves there, but lack the knowledge of anything outside of that. But no matter what is done, it always needs to be taken back to your original base, otherwise it isn't going to amount to anything.
Hope none of this was too harsh,
Chris.
You dont have to limit your replies to just those questions. And as always, this discussion is open to non Kenpoists as well. 
Take the basics, drill the hell out of them, and add in some Kenpo where its applicable. 
